The former United captain told the Sunday Mirror: "At United you are treated like a king from the moment you walk through the door until the moment you leave."
Bruce, who made 309 appearances for United between 1987 and 1996, added: "When you are at that club as a player you don't need to do anything other than perform, everything else is taken care of for you. Everything about United is top drawer and Sir Alex makes sure that he treats everybody with huge respect.
"That's one thing Fergie does more than maybe anyone - he is fiercely protective of his players.
"So for someone to say the players are treated like slaves baffles me."